Many integrated circuits require a stable reference voltage for their operation. For example, voltage references are used in data acquisition systems, voltage regulators and measurement equipment. Two types of voltage references are commonly used in such integrated circuits: bandgap-voltage references and buried-Zener references.
Bandgap-voltage references provide several advantages over buried-Zener references. Bandgap voltage references can operate with a lower supply voltage than buried-Zener references and also dissipate less power. Further, long-term stability of a bandgap voltage reference exceeds that of a buried-Zener reference.
Unfortunately, the output voltage of a bandgap voltage reference is more dependent upon temperature than is a buried-Zener reference. This factor becomes important if the integrated circuit is to be subjected to a wide range of temperatures, for example, if it is used outdoors. It should be noted that both bandgap-voltage references and buried-Zener references provide output voltages which are temperature-dependent to some degree.
Therefore, a need has arisen in the industry to provide a reference voltage source which provides a stable output voltage over a wide temperature range.